Many oil refinery and chemical plant units utilize nozzles for distributing liquid and/or gaseous feed to the unit. In some units, the ability of the nozzle to distribute the feed to the unit is very important to the productivity of the unit. For example, a catalytic cracking unit converts large chain hydrocarbon molecules found in crude oil into smaller and more valuable commercial products such as gasoline range hydrocarbons and diesel oils. Typically, vacuum distillates are introduced through feed nozzles in an upflow riser reactor where the feed is contacted with regenerated particulate solid catalysts. The catalyst selectively aids desirable cracking reactions.
For peak performance of the reactor, it is essential that the nozzle distribute the feed in a fine spray having a uniform coverage and a narrow droplet size distribution. Such a spray increases the surface area of the feed droplets and facilitates contacting with the catalyst particles. Existing nozzles have difficulty, however, in achieving this desired performance. Some nozzles use very small openings or complex tip designs which easily become plugged by various impurities in the feed or by coking. The down time and replacement expense in repairing such a blockage is very disadvantageous. Existing nozzles also cannot produce sufficiently fine droplets and/or a desirable spray pattern. Existing nozzles also are not adjustable in their angle of spray relevant to the axis of the feed conduits to which the nozzles are attached.
For riser reactors with currently available nozzle designs, the adjustment of the injection angle of the feed requires expensive modifications of the apparatus. It would be desirable to be able to only replace the feed nozzle in order to adjust the feed injection angle without the need for other equipment modifications.
Accordingly, it would be advantageous to have a nozzle capable of achieving a narrow distribution of fine droplets, a thin layer of uniform spray, and not having a tendency for blockage.